1"""
2======================================
3Radar chart (aka spider or star chart)
4======================================
5
6This example creates a radar chart, also known as a spider or star chart [1]_.
7
8Although this example allows a frame of either 'circle' or 'polygon', polygon
9frames don't have proper gridlines (the lines are circles instead of polygons).
10It's possible to get a polygon grid by setting GRIDLINE_INTERPOLATION_STEPS in
11matplotlib.axis to the desired number of vertices, but the orientation of the
12polygon is not aligned with the radial axes.
13
14.. [1] http://en.wikipedia.org/wiki/Radar_chart
15"""
16import numpy as np
17
18import matplotlib.pyplot as plt
19from matplotlib.path import Path
20from matplotlib.spines import Spine
21from matplotlib.projections.polar import PolarAxes
22from matplotlib.projections import register_projection
23
24
25def radar_factory(num_vars, frame='circle'):
26    """Create a radar chart with `num_vars` axes.
27
28    This function creates a RadarAxes projection and registers it.
29
30    Parameters
31    ----------
32    num_vars : int
33        Number of variables for radar chart.
34    frame : {'circle' | 'polygon'}
35        Shape of frame surrounding axes.
36
37    """
38    # calculate evenly-spaced axis angles
39    theta = np.linspace(0, 2*np.pi, num_vars, endpoint=False)
40
41    def draw_poly_patch(self):
42        # rotate theta such that the first axis is at the top
43        verts = unit_poly_verts(theta + np.pi / 2)
44        return plt.Polygon(verts, closed=True, edgecolor='k')
45
46    def draw_circle_patch(self):
47        # unit circle centered on (0.5, 0.5)
48        return plt.Circle((0.5, 0.5), 0.5)
49
50    patch_dict = {'polygon': draw_poly_patch, 'circle': draw_circle_patch}
51    if frame not in patch_dict:
52        raise ValueError('unknown value for `frame`: %s' % frame)
53
54    class RadarAxes(PolarAxes):
55
56        name = 'radar'
57        # use 1 line segment to connect specified points
58        RESOLUTION = 1
59        # define draw_frame method
60        draw_patch = patch_dict[frame]
61
62        def __init__(self, *args, **kwargs):
63            super(RadarAxes, self).__init__(*args, **kwargs)
64            # rotate plot such that the first axis is at the top
65            self.set_theta_zero_location('N')
66
67        def fill(self, *args, **kwargs):
68            """Override fill so that line is closed by default"""
69            closed = kwargs.pop('closed', True)
70            return super(RadarAxes, self).fill(closed=closed, *args, **kwargs)
71
72        def plot(self, *args, **kwargs):
73            """Override plot so that line is closed by default"""
74            lines = super(RadarAxes, self).plot(*args, **kwargs)
75            for line in lines:
76                self._close_line(line)
77
78        def _close_line(self, line):
79            x, y = line.get_data()
80            # FIXME: markers at x[0], y[0] get doubled-up
81            if x[0] != x[-1]:
82                x = np.concatenate((x, [x[0]]))
83                y = np.concatenate((y, [y[0]]))
84                line.set_data(x, y)
85
86        def set_varlabels(self, labels):
87            self.set_thetagrids(np.degrees(theta), labels)
88
89        def _gen_axes_patch(self):
90            return self.draw_patch()
91
92        def _gen_axes_spines(self):
93            if frame == 'circle':
94                return PolarAxes._gen_axes_spines(self)
95            # The following is a hack to get the spines (i.e. the axes frame)
96            # to draw correctly for a polygon frame.
97
98            # spine_type must be 'left', 'right', 'top', 'bottom', or `circle`.
99            spine_type = 'circle'
100            verts = unit_poly_verts(theta + np.pi / 2)
101            # close off polygon by repeating first vertex
102            verts.append(verts[0])
103            path = Path(verts)
104
105            spine = Spine(self, spine_type, path)
106            spine.set_transform(self.transAxes)
107            return {'polar': spine}
108
109    register_projection(RadarAxes)
110    return theta
111
112
113def unit_poly_verts(theta):
114    """Return vertices of polygon for subplot axes.
115
116    This polygon is circumscribed by a unit circle centered at (0.5, 0.5)
117    """
118    x0, y0, r = [0.5] * 3
119    verts = [(r*np.cos(t) + x0, r*np.sin(t) + y0) for t in theta]
120    return verts
121
122
123def example_data():
124    # The following data is from the Denver Aerosol Sources and Health study.
125    # See  doi:10.1016/j.atmosenv.2008.12.017
126    #
127    # The data are pollution source profile estimates for five modeled
128    # pollution sources (e.g., cars, wood-burning, etc) that emit 7-9 chemical
129    # species. The radar charts are experimented with here to see if we can
130    # nicely visualize how the modeled source profiles change across four
131    # scenarios:
132    #  1) No gas-phase species present, just seven particulate counts on
133    #     Sulfate
134    #     Nitrate
135    #     Elemental Carbon (EC)
136    #     Organic Carbon fraction 1 (OC)
137    #     Organic Carbon fraction 2 (OC2)
138    #     Organic Carbon fraction 3 (OC3)
139    #     Pyrolized Organic Carbon (OP)
140    #  2)Inclusion of gas-phase specie carbon monoxide (CO)
141    #  3)Inclusion of gas-phase specie ozone (O3).
142    #  4)Inclusion of both gas-phase species is present...
143    data = [
144        ['Sulfate', 'Nitrate', 'EC', 'OC1', 'OC2', 'OC3', 'OP', 'CO', 'O3'],
145        ('Basecase', [
146            [0.88, 0.01, 0.03, 0.03, 0.00, 0.06, 0.01, 0.00, 0.00],
147            [0.07, 0.95, 0.04, 0.05, 0.00, 0.02, 0.01, 0.00, 0.00],
148            [0.01, 0.02, 0.85, 0.19, 0.05, 0.10, 0.00, 0.00, 0.00],
149            [0.02, 0.01, 0.07, 0.01, 0.21, 0.12, 0.98, 0.00, 0.00],
150            [0.01, 0.01, 0.02, 0.71, 0.74, 0.70, 0.00, 0.00, 0.00]]),
151        ('With CO', [
152            [0.88, 0.02, 0.02, 0.02, 0.00, 0.05, 0.00, 0.05, 0.00],
153            [0.08, 0.94, 0.04, 0.02, 0.00, 0.01, 0.12, 0.04, 0.00],
154            [0.01, 0.01, 0.79, 0.10, 0.00, 0.05, 0.00, 0.31, 0.00],
155            [0.00, 0.02, 0.03, 0.38, 0.31, 0.31, 0.00, 0.59, 0.00],
156            [0.02, 0.02, 0.11, 0.47, 0.69, 0.58, 0.88, 0.00, 0.00]]),
157        ('With O3', [
158            [0.89, 0.01, 0.07, 0.00, 0.00, 0.05, 0.00, 0.00, 0.03],
159            [0.07, 0.95, 0.05, 0.04, 0.00, 0.02, 0.12, 0.00, 0.00],
160            [0.01, 0.02, 0.86, 0.27, 0.16, 0.19, 0.00, 0.00, 0.00],
161            [0.01, 0.03, 0.00, 0.32, 0.29, 0.27, 0.00, 0.00, 0.95],
162            [0.02, 0.00, 0.03, 0.37, 0.56, 0.47, 0.87, 0.00, 0.00]]),
163        ('CO & O3', [
164            [0.87, 0.01, 0.08, 0.00, 0.00, 0.04, 0.00, 0.00, 0.01],
165            [0.09, 0.95, 0.02, 0.03, 0.00, 0.01, 0.13, 0.06, 0.00],
166            [0.01, 0.02, 0.71, 0.24, 0.13, 0.16, 0.00, 0.50, 0.00],
167            [0.01, 0.03, 0.00, 0.28, 0.24, 0.23, 0.00, 0.44, 0.88],
168            [0.02, 0.00, 0.18, 0.45, 0.64, 0.55, 0.86, 0.00, 0.16]])
169    ]
170    return data
171
172
173if __name__ == '__main__':
174    N = 9
175    theta = radar_factory(N, frame='polygon')
176
177    data = example_data()
178    spoke_labels = data.pop(0)
179
180    fig, axes = plt.subplots(figsize=(9, 9), nrows=2, ncols=2,
181                             subplot_kw=dict(projection='radar'))
182    fig.subplots_adjust(wspace=0.25, hspace=0.20, top=0.85, bottom=0.05)
183
184    colors = ['b', 'r', 'g', 'm', 'y']
185    # Plot the four cases from the example data on separate axes
186    for ax, (title, case_data) in zip(axes.flatten(), data):
187        ax.set_rgrids([0.2, 0.4, 0.6, 0.8])
188        ax.set_title(title, weight='bold', size='medium', position=(0.5, 1.1),
189                     horizontalalignment='center', verticalalignment='center')
190        for d, color in zip(case_data, colors):
191            ax.plot(theta, d, color=color)
192            ax.fill(theta, d, facecolor=color, alpha=0.25)
193        ax.set_varlabels(spoke_labels)
194
195    # add legend relative to top-left plot
196    ax = axes[0, 0]
197    labels = ('Factor 1', 'Factor 2', 'Factor 3', 'Factor 4', 'Factor 5')
198    legend = ax.legend(labels, loc=(0.9, .95),
199                       labelspacing=0.1, fontsize='small')
200
201    fig.text(0.5, 0.965, '5-Factor Solution Profiles Across Four Scenarios',
202             horizontalalignment='center', color='black', weight='bold',
203             size='large')
204
205    plt.show()
206